1. Field of the Invention
Aspects of the present invention relate to an image forming apparatus. More particularly, aspects of the present invention relate to a power transmitter for delivering power to a plurality of feeding rollers in an image forming apparatus, and an image forming apparatus having the same.
2. Description of the Related Art
Generally, an image forming apparatus performs a printing operation through supplying print media, forming a predetermined image on a print medium, and discharging the print medium whereon the image is formed to the outside.
FIG. 1 is a partial side view schematically showing a conventional image forming apparatus. Referring to FIG. 1, a conventional image forming apparatus 1 comprises a print media supply unit 3, a print media feeding unit 4, and an image formation unit 5.
The print media feeding unit 4, as shown in FIGS. 1 and 2, comprises a plurality of first and second feeding rollers 22 and 26, a power transmitter 20, and a plurality of print media sensors 41 and 42. The plurality of second feeding rollers 26 feed a print medium (not shown) supplied by a pickup roller 11 to the plurality of first feeding rollers 22. The plurality of first feeding rollers 22 feed the print medium being supplied by the plurality of second feeding rollers 26 toward the image formation unit 5.
The power transmitter 20 comprises a first feeding roller rotation shaft 21 for rotating the plurality of first feeding rollers 22, a second feeding roller rotation shaft 25 for rotating the plurality of second feeding rollers 26, a driving motor 29 and a driving gear train 30 for driving the first and the second feeding roller rotation shafts 21 and 25, and a support bracket 37 fixed to a frame 2 of the image forming apparatus 1 supporting the driving motor 29 and the driving gear train 30. A first transmission gear 23 is mounted coaxially with one end of the first feeding roller rotation shaft 21 to receive power from the driving motor 29 through the driving gear train 30. A second transmission gear 27 is mounted coaxially with one end of the second feeding roller rotation shaft 25. The first and the second transmission gears 23 and 27 are meshed with each other. The driving gear train 30 comprises first, second, and third intermediate gears 31, 32 and 33. The third intermediate gear 33 is meshed with the first transmission gear 23.
Additionally, a plurality of first and second feeding idle rollers 24 and 28 are mounted to rotate in contact with the plurality of first and second feeding rollers 22 and 26, respectively.
In FIG. 2, an image formation gear 35 rotates the image formation unit 5 that produces an image on the print medium supplied by the first feeding roller 22, and a fixing gear 36 rotates a fixing unit (not shown) that fixes the image formed on the print medium. In FIG. 3, a pickup gear 13 is coaxially connected to the pickup roller 11.
The plurality of print media sensors 41 and 42 detect a location of the print medium. More particularly, the first print media sensor 41 detects the print medium when the print medium contacts the first feeding roller 22 while the second print media sensor 42 detects the print medium when the print medium contacts the image formation unit 5.
Hereinbelow, the operation of the conventional image forming apparatus will be described with reference to FIGS. 1 and 2.
When a control unit (not shown) receives a printing command, the pickup roller 11 picks up a sheet of the print medium that is stacked in a print media stacking member 12 and feeds the print medium between the second feeding roller 26 and the second feeding idle roller 28. As the driving motor 29 is rotated herein, the first transmission gear 23 is rotated by the driving gear train 30. As the first transmission gear 23 is rotated, the second transmission 27 meshed with the first transmission gear 23 is accordingly rotated. According to a rotation of the first and the second transmission gears 23 and 27, the first and the second feeding roller rotation shafts 21 and 25 coaxially connected with the first and the second transmission gears 23 and 27 are rotated. Then, the first and the second feeding rollers 22 and 26 coaxially connected with the first and the second feeding roller rotation shafts 21 and 25 are rotated. As a result, the first and the second feeding idle rollers 24 and 28 that are in contact with the first and the second feeding rollers 22 and 26 are rotated. Consequently, the print medium fed between the second feeding roller 26 and the second feeding idle roller 28 by the pickup roller 11 is fed to the image formation unit 5 through the second feeding and the second feeding idle rollers 26 and 28, and the first feeding and the first feeding idle rollers 22 and 24. The image formation unit 5 forms an image on the print medium according to the printing command and feeds the print medium bearing thereon the image to the fixing unit (not shown). The fixing unit fixes the image onto the print medium and feeds the print medium to a discharge unit (not shown). As the discharge unit ejects the print medium to the outside of the image forming apparatus 1, the printing work is completed. The control unit appropriately controls the above processes by perceiving the location of the print medium through the first and the second print media sensors 41 and 42.
In the above-structured image forming apparatus 1, the first and the second feeding rollers 22 and 26 for feeding the picked-up print medium to the image formation unit 5 are disposed on the first and the second feeding roller rotation shafts 21 and 25, respectively. Each one end of the first and the second feeding roller rotation shafts 21 and 25 is coaxially connected with the first and the second transmission gears 23 and 27 to receive power through the driving gear train 30 mounted at one end of the image forming apparatus 1. The connection structure between the driving gear train 30 and the first and the second transmission gears 23 and 27 is shown in FIG. 3. Thus, in the conventional image forming apparatus 1, a space having a predetermined height h is required in order for power transmission from the driving motor 29 (FIG. 2) to the first and the second feeding roller rotation shafts 21 and 25 through the driving gear train 30. Generally, the conventional image forming apparatus 1 has a height H of approximately 250˜300 mm for the space. The height H includes the predetermined height h required for power transmission to the first and the second feeding roller rotation shafts 21 and 25.
The image forming apparatus 1 is now commonly used domestically, being usually put on a desk at home. However, in this case, a size of the image forming apparatus 1, especially the height H of the image forming apparatus 1, is too high for convenient use. Generally, as the height of the image forming apparatus 1 increases, volume and weight of the image forming apparatus 1 accordingly increase, thereby making handling and portage of the image forming apparatus difficult.
Although there has been much research for reducing the height of the image forming apparatus 1, it is difficult to remarkably reduce the height when the power transmitter for transmitting power to the plurality of feeding rollers is not omitted.